The broad aim of this research project is to contribute to the further understanding of concept development. Our objective is to validate the hypothesis that the processes involved in the formation of experimentally induced chunks, using normal adult subjects, are similar to those involved in the prelogical child's formation of concepts. The project will explore the relationship between concept and chunk utilization. Recent experimentation has demonstrated that with well- established concepts, such as color and form, the ease of rule learning is ordered in the following manner: conjunctive yields disjunctive yields conditional yields biconditional rules. Tests will be conducted to investigate the relative ordering of rules using experimentally induced chunks and the results compared with those found with known concepts. A principal objective also is to continue work toward the development of a standardized technique for assessing those factors that facilitate or retard concept formation. One such variable we propose to study is the temporal sequencing of stimulus input. A final study will be conducted to directly test predictions generated from our chunking model using preschool and school aged children as subjects.